Effect Of Central Fatigue Research Articles

Beneficial effect of compound essential oil inhalation on central fatigue

BackgroundsAlthough the physical and mental enhancement effect of essential oils have been proved, the beneficial effect of essential oil in central fatigue remains unclear. In this study, we extracted essential oils from nine aromatic plants to make a compound essential oil, and detected the therapeutic effect of central fatigue by daily aerial diffusion.MethodsThirty-three rats were randomly and equally divided into control group, chronic sleep deprivation group, and compound essential oil inhalation group. Central fatigue was generated by chronic sleep deprivation.ResultsAfter 21-day various interferences, it is found that the sleep deprivation rats showed an evident decrease in physical endurance, negative emotion, and cognitive dysfunction compared with the control group, and the group that treated with the compound essential oil behaved significantly better than central fatigue group.ConclusionWe concluded that this formula of essential oils could alleviate central fatigue on rats, and our study provides a new direction of application of aromatic therapy, which could be expanded to insomnia, depression and other healthy issue in the further research.

The Impacts of Central Fatigue on the Polyphasic Nature of Tapping Performance

Objective: As a non-specific symptom muscle fatigue mostly accompanies neuromuscular diseases and also occurs frequently in healthy individuals. Fatigue phenomenon is considered to be multidimensional symptom. There have been still discussions on the origin whether it depends primarily on the intrinsic properties of muscle itself (peripheral mechanisms) or the nervous system that controls muscle (central mechanisms). This study aimed to investigate the effects of central fatigue on the performance of maximal voluntary repetitive movement and discusses the specificity of finger tapping task test as a simple diagnostic tool for fatigue. Methods: For this purpose, 27 healthy, male, right-handed volunteer performed the 20-s of finger tapping task test for four times. The one was for control and the other three were performed right after induction of three different central fatigue models. Temporal behavior of tapping performances were evaluated based on inter-tap intervals and the statistical comparison were made by regression analysis. Results: The results showed that the partial evaluation of the task in time domain instead of complete test period yielded with statistically significant differences between control and fatigue models (p<0.001) and even in between the fatigue models. Conclusion: Approximately the first 5-s of a finger tapping task consists of both motor learning processes and dynamics of energy consumption from anaerobic sources. However, it reflects dominantly the central components of fatigue. We may conclude that the temporal behavior of tapping performance following the induction of specific fatigue model may help making further discrimination for the origin of fatigue.

Central fatigue and sympathovagal imbalance during night shift in Japanese female nurses

The aim of this study was to examine the hypothesis that Japanese female nurses with a reduced total power (TP) component of heart rate variability (HRV) will show an imbalance in sympathovagal activity during night-time work. We carried out this study on 10 healthy female nurses (30.9 ± 3.1 years) working a night shift from 16:00 to 09:00. Heart rate (HR) and the different frequency power components of HRV were measured to estimate individual patterns of sympathovagal activity. A latent imbalance of sympathovagal activity was defined as higher HR and reduced TP, and subjects were divided into two groups based on TP values taken before the night shift. To evaluate central fatigue, we performed three different fatigue tests before and after night work in all subjects. Our results suggest that nurses with reduced HRV have an imbalance of sympathovagal activity but do not suffer from the effects of central fatigue.

Sustained contraction at very low forces produces prominent supraspinal fatigue in human elbow flexor muscles

During sustained maximal voluntary contractions (MVCs), most fatigue occurs within the muscle, but some occurs because voluntary activation of the muscle declines (central fatigue), and some of this reflects suboptimal output from the motor cortex (supraspinal fatigue). This study examines whether supraspinal fatigue occurs during a sustained submaximal contraction of 5% MVC. Eight subjects sustained an isometric elbow flexion of 5% MVC for 70 min. Brief MVCs were performed every 3 min, with stimulation of the motor point, motor cortex, and brachial plexus. Perceived effort and pain, elbow flexion torque, and surface EMGs from biceps and brachioradialis were recorded. During the sustained 5% contraction, perceived effort increased from 0.5 to 3.9 (out of 10), and elbow flexor EMG increased steadily by approximately 60-80%. Torque during brief MVCs fell to 72% of control values, while both the resting twitch and EMG declined progressively. Thus the sustained weak contraction caused fatigue, some of which was due to peripheral mechanisms. Voluntary activation measured by motor point and motor cortex stimulation methods fell to 90% and 80%, respectively. Thus some of the fatigue was central. Calculations based on the fall in voluntary activation measured with cortical stimulation indicate that about two-thirds of the fatigue was due to supraspinal mechanisms. Therefore, sustained performance of a very low-force contraction produces a progressive inability to drive the motor cortex optimally during brief MVCs. The effect of central fatigue on performance of the weak contraction is less clear, but it may contribute to the increase in perceived effort.

Effects of somatosensory input on central fatigue: a pilot study

Objective: Depression of motor evoked potentials (MEPs) following transcranial magnetic stimulation (TMS) may be a sign of central motor fatigue. As a pilot study, we have examined whether post-exercise MEP depression can be compensated by application of sensory stimuli prior to TMS.Methods: We studied 15 healthy volunteers (aged 21–28 years) who were required to perform an exercise protocol of ankle dorsiflexion until force fell below 66% of maximum force. MEPs were recorded from the right tibialis anterior muscle. Prior to TMS, electrical stimuli were applied to the ipsilateral sural nerve with an individual interstimulus interval between 50 and 80 ms.Results: MEP areas decreased after exercise. When a sensory stimulus was administered MEPs did not change.Conclusion: We conclude that the effects of central fatigue may be influenced by application of sensory stimuli.